With the advent of alternative fuels like alcohol, biodiesel and mixed fuels like, E85 (85% ethanol and 15% gasoline) and M85 (85% methanol and 15% gasoline) there is a desire to use them in motor vehicles, motorboats and other motorized machines like trucks, tractors, lawnmowers, etc. With gasoline and diesel prices rising to record levels, alternate fuels are starting to make inroads with average American consumers. Also atmospheric pollution generated by exhaust emissions from conventional gasoline or diesel powered internal combustion engines is a well-documented problem. One method used widely today to reduce noxious emissions is to mix or even replace conventional fuels with cleaner burning alternative fuels. For example, U.S. Pat. Nos. 4,635,608 and 4,711,223 issued to Carroll teach an alcohol-fueled engine. Not only do alternate fuels burn cleaner with less harmful air pollution, the fuels can be made here at home in the United States from a variety of agricultural feedstock thereby reducing the consumption of foreign oil.
The reduction of foreign crude oil has become a topic of high priority in the US since the terrorist attacks of Sep. 11, 2001. Increase consumption of crude oil by Third World countries and the war in Iraq and further instability in the Middle East have contributed to a weak supply of crude and thus the recent rise in gasoline prices. The number of total vehicles on the planet today is estimated to be around 500 million, most of which are in the USA. By 2050 it is estimated that there will be over 3 billion vehicles and most of that increase will be in Asia and in particular China. It is reasonable to expect that crude oil prices will continue to rise whereby increasing the need of alternate fuels.
A motor vehicle capable of burning mixtures of gasoline and alcohol is commonly called a Flexible Fuel Vehicle (FFV). Today's commercially available FFVs typically burn any mixture from 85% ethanol or methanol to 100% gasoline. A diesel FFV can burn any mixture of diesel and biodiesel and ethanol is also known to be mixed with diesel. The operation of a FFV is well known and taught in a number of patents. U.S. Pat. No. 4,945,863 issued to Schmitz, et al. for example, describes a fuel-burning engine, which uses a mixed fuel containing alcohol from a single reservoir or tank. The fuel to alcohol ratio is measured using a sensor and the result is used to control the quantity of fuel being fed into the engine. U.S. Pat. No. 4,995,367 issued to Yamauchi et al. discloses a system for controlling both fuel injection and timing in an internal combustion engine operating on a fuel mixture of gasoline and methanol.
Controlling the quantity of fuel is necessary because alcohol fuels like ethanol and methanol have less energy per unit volume than gasoline or diesel and require a much smaller air to fuel ratio when burned in an internal combustion engine. While gasoline has an ideal air to fuel ratio of 14.7 to 1, pure ethanol has a ratio of about 9 to 1. The proper required air to fuel ratio is commonly referred to as stoichiometric. A fuel injection system in a FFV instantly compensates to maintain stoichiometric over wide percentage changes in the fuel mix. Therefore the principal advantage of a FFV is its ability to arbitrarily be refueled both with pure fuels and mixed fuels. This type of refueling is important because in early 2005 only about 200 service stations in 22 States in the US currently dispense mixed fuels like E85.
Some electronic fuel injection systems used in FFVs incorporate the use of a fuel composition sensor in combination with an Engine Controller Module (ECM). There are several different types of fuel composition sensors. One such sensor, an infrared sensor, is disclosed in U.S. Pat. No. 4,594,968 issued to Degobert et al. Another is a capacitive sensor taught in U.S. Pat. No. 4,915,084 issued to Eugene V. Gonze. Fuel composition sensors provide information to the ECM about the concentration of alternate fuel in the fuel mixture. Generally, fuel composition sensors provide a signal that is directly related to the percentage of alternate fuel in the fuel mixture. From that information the ECM calculates the suitable air to fuel ratio need for proper combustion. The ECM typically regulates the air to fuel mixture by controlling the amount of fuel being injected into the intake system of the engine for any given mass of air.
In the late 1990s, automotive manufactures began producing FFVs. The motivating force behind the emergence of FFVs was Federal energy legislation directed by the EPA. The demand for FFVs over the past 5 years has been rather small with the largest consumer being Federal and State governments. FFVs are currently available from six different automotive manufacturers but in just a few models. This year for example the Ford Motor Company manufactures only the Ford Taurus sedan and the Ford Explorer SUV with a FFV option. Even though FFVs make up a small percentage of vehicle sales there is a growing need for FFVs. The need is being driven mostly by the rise in crude oil prices and the desire for reduced exhaust emissions. Since there are only a few vehicle models made as FFVs, there is growing need to modify previously manufactured vehicles like classic cars, trucks and SUVs to make them fuel flexible. Classic cars and modern sports cars with high compression engines typically get poor gas mileage, have high levels of emissions and will additionally benefit from the high octane of alcohol based alternate fuels.
Therefore there is a need to convert conventional gasoline and diesel burning vehicles already being used on the highways today into Flexible Fuel Vehicles. Since these vehicles were not manufactured to operate on alternate fuels the addition of a flexible fuel engine control system is needed. In the case of a classic car using a carburetor, one method would be to replace the carburetor system with a complete flexible fuel injection system including components like, fuel injectors, sensors and an ECM. Another method would be to add a supplemental flexible fuel injection system to the engine in combination with the carburetor. For modern vehicles manufactured with Electronic Fuel Injection (EFI) it would be preferred to avoid redundancy and add or replace only the essential components for flexible fuel control.
Another complicating factor to converting any modern vehicle's fuel system is the costs and delays associated in obtaining EPA approvals. Federal law prohibits changes to a vehicle that would have an effect upon its exhaust emissions. Modifying a vehicle's fuel system generally requires an EPA or CARB approval on the modified engine. With few OEM models made available as FFVs there is a need to convert older vehicles into FFVs and in such a way to reduce the costs associated with EPA approvals for those vehicles.